Tor and the Sin3-Rpd3 complex regulate expression of the mitophagy receptor protein Atg32 in yeast

J Cell Sci. 2014 Jul 15;127(Pt 14):3184-96. doi: 10.1242/jcs.153254. Epub 2014 May 16.

Abstract

When mitophagy is induced in Saccharomyces cerevisiae, the mitochondrial outer membrane protein ScAtg32 interacts with the cytosolic adaptor protein ScAtg11. ScAtg11 then delivers the mitochondria to the pre-autophagosomal structure for autophagic degradation. Despite the importance of ScAtg32 for mitophagy, the expression and functional regulation of ScAtg32 are poorly understood. In this study, we identified and characterized the ScAtg32 homolog in Pichia pastoris (PpAtg32). Interestingly, we found that PpAtg32 was barely expressed before induction of mitophagy and was rapidly expressed after induction of mitophagy by starvation. Additionally, PpAtg32 was phosphorylated when mitophagy was induced. We found that PpAtg32 expression was suppressed by Tor and the downstream PpSin3-PpRpd3 complex. Inhibition of Tor by rapamycin induced PpAtg32 expression, but could neither phosphorylate PpAtg32 nor induce mitophagy. Based on these findings, we conclude that the Tor and PpSin3-PpRpd3 pathway regulates PpAtg32 expression, but not PpAtg32 phosphorylation.

Keywords: Atg32; Autophagy; Mitochondria; Mitophagy; Rpd3; Sin3; Tor; Yeast.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / physiology*
  • Autophagy-Related Proteins
  • Protein Binding
  • Receptors, Cytoplasmic and Nuclear / genetics*
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Sin3 Histone Deacetylase and Corepressor Complex / metabolism*
  • Vesicular Transport Proteins / metabolism

Substances

  • Atg32 protein, S cerevisiae
  • Autophagy-Related Proteins
  • Receptors, Cytoplasmic and Nuclear
  • Saccharomyces cerevisiae Proteins
  • Vesicular Transport Proteins
  • Sin3 Histone Deacetylase and Corepressor Complex